XK0-005 Scripting, Containers and Automation Practice Test 4 — 15 Questions

Question 1

A container needs to communicate with a database on the host machine using the default bridge network. The container cannot resolve the host by hostname. Which approach should be used?

Accepted Answer

Use --add-host host.docker.internal:host-gateway. Option D is correct because `--add-host host.docker.internal:host-gateway` adds a special entry to the container's `/etc/hosts` file that resolves `host.docker.internal` to the host machine's gateway IP address, which on the default bridge network is the host itself. This allows the container to reach the host by a consistent hostname without relying on Docker's internal DNS, which does not resolve hostnames on the default bridge. The `host-gateway` magic value automatically maps to the host's IP (typically 172.17.0.1 on Linux).

Answer

Set --net=host

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Use --link db:db

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Create a custom bridge network

Question 2

What does the `set -x` command do when placed at the top of a bash script?

Accepted Answer

Displays each command before executing it. Option D is correct because `set -x` enables a shell debugging mode that prints each command (after expansion) to stderr before executing it. This is commonly used in bash scripts to trace execution flow and debug complex logic.

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Enables position parameters

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Exits the script on error

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Treats unset variables as errors

Question 3

A DevOps engineer is writing a unit file for a systemd service that should start after the network-online.target. Which directive should be added to the [Unit] section?

Accepted Answer

After=network-online.target. The 'After=' directive in the [Unit] section of a systemd unit file specifies the ordering relationship, ensuring that the current service starts only after the named unit (network-online.target) has reached the 'active' state. This is the correct directive for controlling startup order without creating a dependency that would force the target to start if it is not already enabled.

Answer

Requires=network-online.target

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Wants=network-online.target

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BindsTo=network-online.target

Question 4

A containerized application writes logs to /var/log/app.log. The administrator wants to ensure logs persist even if the container is removed. Which approach should be used?

Accepted Answer

Use a Docker volume mounted at /var/log. Option D is correct because Docker volumes are managed by Docker and persist independently of the container lifecycle. By mounting a volume at /var/log, the application writes logs directly to the volume, ensuring the data survives container removal and can be reused by other containers.

Answer

Copy logs to a bind mount

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Set the log driver to syslog

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Redirect logs to stdout and use docker logs

Question 5

Which two of the following are valid methods to pass environment variables to a Docker container at runtime? (Select TWO.)

Accepted Answer

Defining variables in a .env file and using --env-file. Option A is correct because the `--env-file` flag in `docker run` allows you to pass environment variables from a file (typically a `.env` file) to the container at runtime. This method is useful for managing multiple variables without cluttering the command line and supports variable substitution and quoting rules as defined by Docker.

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Using the ENV instruction in the Dockerfile

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Using the export command inside the container

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Using the ARG instruction in the Dockerfile

Question 6

A system administrator is troubleshooting a bash script that fails when run from cron but works when run from the terminal. Which two factors could explain this behavior? (Select TWO.)

Accepted Answer

The script uses interactive commands. Option A is correct because interactive commands (e.g., `read`, `select`, or commands that require a TTY) fail when run from cron, as cron does not allocate a terminal. The script expects user input or terminal interaction, which is not available in the cron environment, causing it to hang or error out. Option E is correct because cron runs with a minimal PATH (often `/usr/bin:/bin`), so the script may fail to locate commands that are found in the user's interactive shell PATH (e.g., `/usr/local/bin`).

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The script uses a different shell interpreter

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The script uses absolute paths

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The script runs with a different user ID

Question 7

A Linux administrator is writing a systemd service unit file. Which three of the following directives are valid in the [Service] section? (Select THREE.)

Accepted Answer

Restart. A is correct because `Restart` is a valid directive in the `[Service]` section of a systemd service unit file. It controls whether and how the service is restarted when it exits, with common values like `always`, `on-failure`, or `no`. This directive is essential for ensuring service resilience in production environments.

Answer

After

Answer

Requires

Question 8

Refer to the exhibit. A Docker container using a bind mount fails to start with a permission error. What is the most likely cause?

Accepted Answer

SELinux is blocking the mount.. When a Docker container uses a bind mount and fails with a permission error, SELinux is a common cause because it enforces mandatory access controls that can block container processes from accessing host files. By default, SELinux labels container processes with a confined domain (e.g., container_t), and if the bind-mounted host directory lacks the proper SELinux context (e.g., container_file_t), the mount is denied. This is resolved by adding the `:Z` or `:z` flag to the bind mount in the Docker run command to relabel the host directory appropriately.

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The container is running in privileged mode.

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The Docker daemon is not running as root.

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The volume path on the host does not exist.

Question 9

Refer to the exhibit. The service fails to start with the error 'Failed to start My Service: Unit not found'. What is the most likely cause?

Accepted Answer

The service file is not in the correct directory.. The error 'Unit not found' indicates that systemd cannot locate the service unit file. Systemd service files must be placed in specific directories such as /etc/systemd/system/ or /usr/lib/systemd/system/. If the file is in the wrong directory, systemd will not recognize the unit, causing the 'Unit not found' error. Option B correctly identifies this as the most likely cause.

Answer

The User specified does not exist.

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The network target is not reached.

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The ExecStart script is missing.

Question 10

Refer to the exhibit. A system administrator notices that the cleanup script runs at 2:00 AM every day but sometimes does not execute. The log shows no output from the script. Which step should be taken to investigate?

Accepted Answer

Change the script to log output to a file.. Option D is correct because the script runs but produces no log output, indicating it may be failing silently. Redirecting the script's stdout and stderr to a file (e.g., `>> /var/log/cleanup.log 2>&1`) captures error messages and output, allowing the administrator to see why the script sometimes does not execute or fails. This is the most direct way to diagnose a cron job that runs but yields no visible results.

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Verify that the script is executable by the root user.

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Check the syslog for cron execution messages.

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Add a MAILTO directive to the crontab.

Question 11

A systems administrator needs to automate the execution of a backup script every day at 2:00 AM using a systemd service. Which unit type should the administrator create?

Accepted Answer

A .timer unit. A .timer unit is the correct choice because systemd timers are designed to schedule and trigger the execution of other units (such as services) at specific times or intervals. By creating a .timer unit that activates at 2:00 AM daily and a corresponding .service unit for the backup script, the administrator can automate the backup using systemd's built-in scheduling mechanism, which is more reliable and integrated than cron for systemd-managed systems.

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A .service unit

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A .path unit

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A .mount unit

Question 12

A developer writes a Python script that uses the `requests` library to fetch data from an API. The script works on the developer's workstation but fails on the server with an import error. What is the most likely cause?

Accepted Answer

The `requests` module is not installed on the server. The `requests` library is a third-party Python package that must be installed separately via `pip` or a package manager. The script works on the developer's workstation because `requests` is present there, but fails on the server with an import error, indicating the module is missing from the server's Python environment. This is the most likely cause because an import error specifically points to a missing module, not to network or syntax issues.

Answer

The script uses an incorrect API endpoint

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The server lacks internet connectivity

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The script has a syntax error in the import statement

Question 13

An administrator wants to use Ansible to ensure that the `httpd` package is installed on all managed nodes. Which Ansible module should be used?

Accepted Answer

yum. The `yum` module is the correct choice because it is a dedicated Ansible module for managing packages on Red Hat-based systems using the YUM package manager. It ensures the `httpd` package is installed by setting the `state: present` parameter, and it handles idempotency by checking the package status before making changes.

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copy

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command

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service

Question 14

A DevOps engineer is designing a CI/CD pipeline for a microservices application. The pipeline should build a Docker image, run unit tests, and if successful, push the image to a private registry. Which tool is best suited for orchestrating this pipeline?

Accepted Answer

Jenkins. Jenkins is a widely adopted CI/CD automation server that excels at orchestrating complex pipelines, including building Docker images, running unit tests, and pushing images to a private registry. Its pipeline-as-code feature (Jenkinsfile) allows defining stages, triggers, and post-build actions, making it the best fit for this microservices CI/CD workflow.

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Git

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cron

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Ansible

Question 15

A Linux administrator is writing a Bash script that needs to parse a CSV file line by line and extract the second field. Which of the following approaches is the most efficient?

Accepted Answer

Using `awk -F',' '{print $2}'`. Option B is correct because `awk` is purpose-built for field-based text processing; `awk -F',' '{print $2}'` efficiently splits each line by comma and prints the second field without needing an explicit loop. It handles edge cases like empty fields and large files with minimal overhead, making it the most efficient choice for CSV parsing in a script.

Answer

Using a `while read` loop with IFS=','

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Using `cut -d, -f2`

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Using `sed` to extract the second column